These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Breather Level: The Machine, ironically. It's big and labyrinthine, but there are only two places to die (the twin drains at the bottom), so you can more or less relax and take your time. The Veg-O-Machine itself also turns out to be a Breather Boss... followed right thereafter by a Difficulty Spike up the Ro-butt-nik called "The Showdown".
Nightmare Fuel: Whether intentional or not, this whole game has given many a player nightmares, particularly for the dark level designs, difficulty level, and some rather... frightening sound effects.
Porting Disaster: The Game Gear / Master System version. Although the levels are remarkably similar compared to other Sonic the Hedgehog ports (not necessarily by its own merits), whatever physics existed in the Genesis version were thrown completely out the window. Worse is the platforming engine, in which Sonic has an innate tendency to get himself stuck.
Stop Helping Me!: The game likes to constantly remind you of your objectives if you keep hitting the wrong targets.
Welcome to the first level, Toxic Caves! CLUCK ALERT!
To make progress in Lava Powerhouse, you need to BUST DOOR FIRST or BUST CORK FIRST...
Showdown, the final stage, is particularly bad with this tr—BUST BLOCKS FIRST!